The well-known sailboat has been considered through the ages as an integral unit the main parts of which are the floating means (hull or vessel) and the propelling means (mast and sails).
The methods adopted for designing sailboats precisely consider the same as an integral unit. The analysis thereof has always been highly complex since it was necessary heretofore to simultaneously consider the entire set of interacting factors and variables, thereby requiring huge calculations to determine the appropiate magnitude for each one of them for a specific design. This problem still lasts since the coming of vessels of this type centuries ago in spite of the increase in knowledge of mankind in different scientific subjects related with this topic. The best results are obtained by just a chosen few having innate skill, knack and individual experience who begin with conventional designs which they readjust and retouch until satisfactory results are obtained after a great deal of work.
The design process often involves arriving at "balanced solutions" wherein values for conflicting or divergent variables must be stretched to limits. In addition there inevitably is an excesive range of uncertainty in the final result. Because of this, naval constructors and designers, with the aim of reducing the eventual deviations from the specifications for a new boat, resort to using, as starting point, previous designs having known behaviour. These designs are updated, then lines are readjusted, and proportions and materials are tested to obtain a superior product; however the actual behaviour, qualities or defects are not known until the boat has been launched and tested in water before one can know for sure whether the project is a success or a failure.
It is difficult to study the interactions between the project variables and the practical implications based on tables, scaled models, plans, formulae, charts and calculations to predict the precise behaviour of the project under controlled conditions in an experimental channel. One should remember that practically all studies in an experimental channel are carried out only on the hull of a boat to derive navigavility, floating lines, etc. However, the hull of the boat is always analysed as an independent float; that is, the prototype is not studied together with scaled propulsion means, such as screw propeller, sail or any other such system. This makes the results obtained from studying a wind-impelled floating vessel differ from reality because the actual conditions in which the vessel will sail are variable and very different from those simulated in the experimental field.
An important aspect, for example, are considerations on the water lines which must be defined for a particular vessel and on which most of the chances of success of the boat depend. The design of the water lines, which constitute the loci of the different horizontal planes or flotation planes which together define the final shape of the hull, is even more important in the case of a sail-boat because, as any expert in the art should know, it is in the water lines where the forward travel resistance of the boat lies. Because sail-boats are listed by the wind the water-line or hull profile in contact with the water is not always the same. Hence, it may be said that the final design of the hull is far from ideal or at least not accurate for a certain general resistance. Summarising, the listing or inclination of the boat brings about different and prominently varying geometries of the underwater portion of the hull; therefore the analysis of the forward movement resistance of the hull is complex and an optimum design may not be reached for different speeds. This happens with conventional boats and has not been solved until now. This is why the inclination or listing of a boat is most important.
The consequences of the inclined navigation on the structure of the boat, although some authors consider them less important, are relevant since they generate forces, strains, torques, stresses and torsions which are particular to each condition of inclination, and must be taken into account by a naval designer as factors in his project. In this manner a sailboat project must include all the calculations necessary to achieve an adequate transverse stability both at small and large angles of inclination, apart from the need of an adequate dynamic stability at certain listing angles. This means, in other words, that the boat must be able to absorb certain external energy without listing over more than a certain angle. This is analysed further on with reference to the drawings.
The systematical experimental data for the theoretical determination of the forward resistance, sustentation coeficients, sail resistance, increased resistence in heavy water, etc., are insufficient, hence the theoretical solutions of the boat balance equations are more cualitative than cuantitative and represent no more than simple comparisons between different alternatives. Balanced solutions between fundamental parameters like sail-area, hull/sail-area balance, stability and weight distribution, which are frequently conflicting, are preferably obtained first calculating one parameter and then successively others before recalculating each with succesive iterations, because of the strong interrelationship between variables and parameters characterising a wind-propelled vessel of today. This is because a single structural unit has been considered in which all its components act integrally and the designer is integrally unable to consider the propulsion unit, such as the sail, rigs, mast, etc., individually from the floating means (vessel or hull per se) because it was not possible to consider these two important elements separately until now and less still separated both physically and conceptually, for the analysis and project of a transport means such as a sailboat. Works, studies and projects carried out historically in the field of naval navigation have been limited, particularly insofar a sailing vessel is concerned, to the analysis, modification and optimization of hull lines to reduce the forward resistence of a vessel, the sails to take better advantage of the wind forces, the design of the rigging, its operating elements, connections, etc., which have led to a simplification of the typical manoeuvers of a sail-boat, the keels and the rudders. But it may be said that the novelty introduced by the present invention and to which reference is made hereinafter is without precedent in history either in naval navigation as in any other transport means using sails for propulsion, for which reason no particular reference may be made to prior art for making a comparison between the present invention and the state of the art. The advantages of the present invention will immediately appear from an innovation which, as previously stated, is without precedent in history in general and in this field in particular.